1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. The present invention relates to a process, a machine, manufacture, or a composition of matter. In particular, the present invention relates to, for example, a semiconductor device, a display device, a light-emitting device, a power storage device, an imaging device, a driving method thereof, or a fabrication method thereof. In particular, one embodiment of the present invention relates to a semiconductor device or a method for manufacturing the semiconductor device.
In this specification and the like, the semiconductor device indicates all the devices that can function by utilizing semiconductor characteristics. A transistor and a semiconductor circuit are embodiments of semiconductor devices. In some cases, a memory device, a display device, or an electronic device includes a semiconductor device.
2. Description of the Related Art
Attention has been focused on a technique for forming a transistor using a semiconductor film formed over a substrate having an insulating surface. The transistor is applied to a wide range of electronic devices such as an integrated circuit (IC) or an image display device (display device). A silicon-based semiconductor material is widely known as a material for a semiconductor thin film applicable to a transistor. As another material, an oxide semiconductor has been attracting attention.
For example, Patent Document 1 discloses a transistor including an amorphous oxide semiconductor layer containing indium (In), gallium (Ga), and zinc (Zn) in a channel formation region layer.